Thermostat



G. c. HARRIS July 8, 1941.

THERMOSTAT Filed March 3, 1939 gwuwrvfm 50172 C Harris Patented July '8, 1941 assignments, Orange, N. J.

to Richard J.

THERMOSTAT Gwin C. Harris, Orange,- N. 1.,

assignor, by mesne Fits Maurice,

Application March 8, 1939, Serial No. 259,648

1 Claim.

This invention relates to a balanced double blade opposed bimetallic thermostat, enclosed in abnon-metaliic casing and mechanically adjusta le.

The primary object of the present invention is the provision of a thermostat of this character which, while capable of general use, is designed more particularly for use in connection with a heating pad.

The invention is illustrated in the accompanying drawing in which:

Figure 1 is a longitudinal section. partly in elevation, of the improved thermostat.

Figure 2 is a section on line 2-4 of Figure 1.

Figure 3 is. a" section on line 3-3 of Figure l.

The improved thermostat comprises an open loosely through the block I insulating material is arranged between the bimetallic arms 9, which latter converge block I to the contacts ll. nected to a freely rotatable rod-like element I! having threaded connection at I! with the wall and the block adjusted to correspondingly, in-

ended cylindrical insulating casing I within 0 which is arranged a heating coil 2. The coil is preferably supported by winding on a thin phenol fiber tube 2' and may be arranged as closely placed relative to the bimetallic arms, to be'later described, as possible to make the wattage in the coil as eilective in the temperature as possible. The coil is of materially less length than that of the casing and is arranged in contact with the inner surface of the casing. I

An insulating block I is secured within the casing adjacent one end, the block being longitudinally cut away on its peripheral edge in diametrically opposed positions, as at I. Arranged on each cut away portion is a metallic plate Ii, one

end 6 of each of which is bent laterally at 'l on the block to hold the plate in position. The opposite end of each plate I is bent inwardly, as at I, to overlie the end of the block I, thus securing the plate against endwise movement relative to the block. Each plate 5 is projected lon'gitudinally oi the casing and within the coil 2 as a bimetallic, heat-responsive arm I and the terminal: of the arrn remote from the block are provided with-contacts iii. Obviously, the plate I for the entire length may be bimetallic for convenience.

Obviously, if appropriately constructed, the 1 arms 8 respond to the heat condition induced by the coil 2, correspondingly affecting the contacts I... In the particular guse in a heating pad wherein the thermostat is designed to accurately control heat conditions with minimum degrees v of fluctuation, provision is made for adjusting the contact holding tension of the bimetallic arms I. in order that such arms may automatical y respond to heat degrees of the coil in slight variations.

Tb provide for this adjustment. a block lip! cal hollow fluence the bimetallic arms and render the same less or more sensitive to the heat influence oi the coil in positioning the contacts -II.

In the more particular use of the thermostat in connection with a heating pad, 9. service conductor I6 is led into the casing i in strip form and terminally connected to one oi'the plates I and to the coil. The remaining plate 5 is connected to a strip conductor i1 while the. opposite end of the coil is connected to a strip conductor i8. These conductors lead through the respective ends of the casing and are securely clamped in position by end caps i9 and 20 each having an end projection It to fit snugly in the end of the casing and clamp the wires in position. Beyond the casing the caps are rounded to avoid abrasive eflect on the material of the pad. These caps have the additional eiiect of sealing the casing against rapid ingress and egress 01 air, which results in the contacts making and breaking the circuit in devitalized air at atmospheric pressure.

It is, of course, apparent that the block ii, here illustrated as oi cylindrical term, may obviously be or wedge or conical form if desired, such additional formation the purpose designed and not requiring illustration.

what is claimed to be new is:

An adjustable thermostat including a'cylindricasing open at the respective ends. an insulating block conforming to and accurately fitting the interior surface or the casing, said block' being formed with diametrically opposing flattened recess portions extending throughout the full axial length of the block, a plate fitted in each recess, the plate being bent over the opposing ends of the block inwardly of the bottom of thelrecess to hold the plate against movement longitudinally of the block and form thesole securing means 01' the plate relative to the block, said plates being extended beyond the block toirom the The block II is conbeing conventional for specific ward the opposite end of the casing in the form of convergingbimetallic arms, the free ends of the arms remote from the block having contact points, a coil surrounding the arms and in contact with the interior surface of the casing, the block being formed with a central axial opening extending entirely through the block and being interiorly threaded, a rod cooperating with the threaded opening, a terminal on the rod beyond the block contacting with the plates and serving to adjust the contacts on the plates relative to each other in accordance with the adjustment of the rod in the block, a conductor leading into the casing at one end and connected with one plate and the coil, 0, second conductgr leading into the same end of the casing and connected to the other plate, and a conductor leading into the opposite end of the casing and to the coil and caps removably closing the ends of the casing and trictionally holding the conductors in place, the removal of the cap adjacent the block permitting access to the rod in the block for adjustment of the contacts.

GWIN C. HARRIS. 

